Pneumatic flushing system for self-contained sewage system



-NOV. 10, 1970 co s ETAL 3,538,517

PNEUMATIC FLUSHING SYSTEM FOR SELF-CONTAINED SEWAGE SYSTEM Filed 001;. 7, 1968 INVENTORS I0 ALAN H.CORNISH a RONALD E. DELANEY W/ M, MQg

, ATTORNEY w IO United States Patent 3,538,517 PNEUMATIC FLUSHING SYSTEM FOR SELF-CONTAINED SEWAGE SYSTEM Alan H. Cornish, Kettering, and Ronald E. De Laney,

Dayton, Ohio, assignors to Koehler-Dayton, Inc., Dayton, Ohio, a corporation of Ohio Filed Oct. 7, 1968, Ser. No. 765,566 Int. Cl. E03d /16 U.S. Cl. 4-10 5 Claims ABSTRACT OF THE DISCLOSURE A pneumatic flushing system for a self-contained flushing toilet system includes a reservoir to hold flushing liquid, a venturi having a vacuum line connected to the reservoir, an inlet valve to control the flow of air through the venturi, and a flow restricting valve in the downstream side of the venturi. In operation, the inlet valve is opened while the flow restricting valve remains closed, and therefore a positive pressure will be created to force the liquid within the reservoir into a flushing manifold Within a toilet bowl. After a predetermined time delay, sufficient to empty most of the liquid from the reservoir, the pneumatic system causes the flow restricting valve on the downstream side of the venturi to open thus creating a subatmospheric pressure within the reservoir to draw liquid through a filter from a main holding tank. Another pneumatic circuit closes the inlet valve after the reservoir fills with filtered liquid.

RELATED APPLICATION Reference is hereby made to copending US. patent application Ser. No. 597,642, filed Nov. 29, 1966, and now Pat. No. 3,487,475, for Pneumatically Operated Self-Contained Sewage System, assigned to the same assignee as the present application.

BACKGROUND OF THE INVENTION Various forms of self-contained flushing toilets, particularly for use in vehicles, such as airplanes, trains, and busses, have been proposed, with one such flushing toilet being exemplified in US. Pat. No. 3,067,433. These self-contained toilets usually incorporate a reservoir beneath the toilet bowl, a pump to draw flushing liquid into the reservoir and to circulate the liquid through the bowl back to a main holding tank and a filter in the inlet to the pump. Such units are flushed by actuating the pump.

In another type of self-contained flushing toilet, as disclosed in the above mentioned application Ser. No. 597,642, air pressure is used to charge the reservoir by reducing the air pressure within the reservoir, and to discharge the reservoir by applying thereto a positive air pressure. Control of the air pressure is achieved by employing a venturi having its vacuum line connected to the reservoir and controlling the air flow through the venturi by a valve on its downstream side. Thus, when the downstream side of the venturi is restricted, a positive pressure will be created in the reservoir to cause the liquid contained therein to be discharged through the flushing manifold in the toilet, and when the restriction is removed, the pressure in the flushing tank will be reduced to draw liquid from a main holding tank through a filtered screen to refill the reservoir. In the above mentioned application, a timer is used to control the flow restricting valve on the downstream side of the venturi.

BRIEF SUMMARY OF THE INVENTION This invention relates to an improved pneumatic system for use with a self-contained flushing toilet for applying pressure to a liquid containing reservoir for a predetermined time period to empty the reservoir, and thereafter for creating a subatmospheric pressure in the reservoir to cause it to refill with liquid to a predetermined level.

The invention employs a flush control valve which is momentarily operated to connect a source of air pressure to a venturi which has a vacuum line connected to a liquid containing reservoir. A normally closed valve assembly is placed in the downstream side of the venturi, and as air pressure is initially applied, a positive pressure will be created in the throat section of the venturi and the reservoir causing the reservoir to empty the liquid through the flushing manifold of the toilet. A parallel air supply path supplies air through a metering restrictor where, after a predetermined time delay, suflicient pressure will cause the valve in the downstream side of the venturi to open, permitting air to flow through the venturi and to create a subatmospheric pressure in the reservoir which causes liquid to be drawn into the reservoir through a filter from the main holding tank of the toilet. When the liquid in the reservoir reaches a predetermined level, the vacuum line from the venturi is closed by a float valve causing a decrease in the pressure in the vacuum line of the venturi which actuates means in the inlet valve to shut the system off.

Thus, the pneumatic system of this invention uses no mechanical or electrical timers to control the flow restricting valve on the downstream side of the venturi, and provides means for shutting off the source of air to the system after the liquid reservoir has refilled.

It is therefore an object of this invention to provide an improved pneumatic system for filling and discharging a liquid reservoir wherein the filling of the reservoir causes the air supply to be shut off; to provide such a pneumatic system which is particularly useful with flushing toilets wherein the opening of an inlet valve creates a positive pressure to cause the liquid in the reservoir to be discharged through a flushing manifold in the toilet for a time period sufficient to empty the reservoir, wherein the air supply, when turned on, controls a valve which opens after a predetermined time delay thereafter to cre ate a subatmospheric pressure within the reservoir to cause it to refill by drawing liquid thereinto; and to provide an improved pneumatic system wherein positive pressure Within the liquid reservoir is prevented from exceeding a predetermined amount by controlling the flow restriction on the downstream side of a venturi.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view of a self-contained flushing toilet with the pneumatic elements of the system shown in cross section, and with the pneumatic lines between these elements shown schematically.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a self-contained flushing toilet system is shown which includes a main holding tank 10 formed with a bottom 11, sides 12, and a top 14 through which the discharge from the toilet bowl 15 is received. The toilet bowl incorporates a discharge spout 17 which extends through the top 14 and directs the discharge to one side of the center of the bowl to prevent viewing of the interior of the tank 10 through the bowl 15.

An airtight liquid reservoir 20, mounted Within the tank 10, is provided with a one way valve 22 mounted in the bottom 23 to admit liquid from the main tank 10 into the reservoir 20 through a filter 25. A check valve 26 in the inlet to the reservoir prevents the liquid in the 3 reservoir 20 from flowing into the tank when the pressure is raised above the pressure in the main tank. The liquid within reservoir will be forced out of the reservoir by air pressure through pipe 27 to a manifold 28 which surrounds the bowl 15 to flush the bowl during the flushing cycle of the toilet.

Thus liquid from the main holding tank 10 is drawn through filter into the reservoir 20 when the pressure in the reservoir is less than the pressure in the main tank. During this period, valve 29 prevents return flow of air from bowl 15 through manifold 28 and line 27. Thereafter increasing the pressure within the reservoir will cause the filtered liquid to be directed through pipe 2'7 to the manifold 28 which surrounds the bowl to cause flushing thereof.

A source of low pressure air is applied through a pressure regulator valve 31 to the flush control valve or inlet valve means 32 which includes a body 33 having an inlet 34 connected to the source of air and an outlet 35. A valve 36 within the body controls the flow of air from the inlet 34 to the outlet 35, and in normal operation the valve is either open or closed. The valve 36 is mounted on a diaphragm 37 which forms a first chamber 38 which is in constant communication with the inlet 34, and the second chamber 39 which is in communication with the inlet through a small opening 40 in the diaphragm.

Since the area of the diaphragm in the second chamber 39 is larger than the area of the diaphragm in the first chamber 38 when the valve 36 is in the position shown, and since the pressure in both chambers is equalized through the small opening 40, the diaphragm 37 will be urged toward the first chamber keeping the valve 36 in the closed position. A spring 41 assists in holding the valve in the closed position.

The valve 36 is opened when the handle 42 is depressed. This opens the valve 43 in the second chamber, which relieves the pressure therein by allowing air to pass out the vent 44 to the atmosphere. Since the pressure on the lower side of the diaphragm 37 now exceeds that on the upper side, the diaphragm will move up and the valve 36 will open, and air will flow from the inlet 34 to the outlet 35.

A venturi 45 has its inlet 46 connected to the outlet 35 of the inlet valve means 32, and thus to the source of air pressure when the valve 36 is open. The venturi is provided with two vacuum lines 47 and 48, with the vacuum line 47 being in communication with the reservoir 20.

As soon as valve 36 opens, pressure will be applied through line 48 to the upper side of diaphragm 49 holding valve 43 in the open position. Spring 49a provides suificient load to prevent the return of diaphragm 49 unit a restriction in the venturi vacuum line 47 is created, resulting in an increase in suction in line 48.

Downstream of the venturi is a normally closed valve means 50 which functions to restrict the flow of air through the venturi and thus causes the pressure in the vacuum lines 47 and 48 to become superatmospheric. Thus, positive pressure is created in the reservoir 20, which will force liquid through the line 27 into the manifold surrounding the bowl 15.

A pneumatic line 58 is also connected from the outlet 35 of the inlet valve means to the normally closed valve means 50 to cause it to relieve the flow restriction after a predetermined time delay.

The valve means 50 includes a valve 51 positioned between an inlet port 52 and an outlet port 53. In the preferred embodiment, the outlet port 53 is in communication with the main holding tank 10 which is itself open to the atmosphere through vent 54. The valve 51 is held in the closed position by a spring 55 and is mechanically connected to a diaphragm 57.

After the inlet valve 36 opens, positive pressure will be applied on line 58 to the flow restrictors 60 and 61 which meter the air into a chamber 62. When the pressure in the chamber 62 rises to a value such that the force on the diaphragm 57 plus the load exerted by spring 63 and the load exerted by the positive pressure at the venturi, equals the force exerted by spring 55, the valve 51 will begin to open and allow air to flow through the venturi and into the main holding tank 10.

As the pressure in chamber 62 continues to rise, load will be transferred to diaphragm 57 entirely and at some critical pressure, the load will be sufficient to move valve 51 fully open. The time between the application of pressure to the reservoir 20 and the opening of valve 51 is adjusted by adjustment of the restriction at screw 61 so that the liquid in the reservoir 20 is substantially, but not completely, discharged through the flushing manifold. With the self-contained toilet system described in the above mentioned copending application, approximately ten seconds is suflicient for substantially emptying the reservoir.

Once the valve 51 opens, and air flows freely through the venturi, a subatmospheric pressure will exist in the line 47 which will reduce the pressure in reservoir 20. This will cause liquid in the main tank 10 to flow through the filter 25 into the reservoir 20. 'When the reservoir 20 fills, a float valve 67, preferably a polyethylene ball because its specific gravity is nearly ideal, will close the vacuum line 47 to prevent further liquid from flowing into the reservoir 20. The float valve 67 is held in place by a member 68. A plurality of holes 69 in the member 68 permits liquid freely to pass therethrough to and from the float valve.

When the float valve 67 closes, the vacuum will increase, and this will be reflected in pneumatic line 48 to the inlet valve means 32. This reduction in pressure will act on diaphragm 49 in the inlet valve means to close the valve 43, and as a consequence the pressure in the second chamber 39 will increase due to the air passing through the small opening 40, and diaphragm will move downwardly. Valve 36 will then close and thus terminate the flow of air to and through venturi 45.

A check valve 64 permits air to escape from chamber 62 when pressure in line 58 decays as the system is shut ofl by float valve 67 and inlet valve 32. The valve 64 causes all flow of air entering chamber 62 to pass through restrictions 60 and 61 but permits rapid venting of the air in chamber 62 to reset the valve means 50 to its starting pressure for the next operating cycle of the toilet.

Means to prevent the pressure in the reservoir 20 from exceeding a predetermined value is provided and includes a line 75 from the venturi to the normally closed valve means 50. The pressure on the line 75 is applied against a diaphragm 82. When the force on the diaphragm 82 and the load exerted by spring 63 exceeds the bias of spring 55, the valve 51 will open. The adjustment screw 81 biases spring 63 which acts against diaphragm 82 and also against spring 55, thus providing for limited adjustment of the water flow rate which is dependent on the positive pressure in reservoir 20.

The normal operation of the system is for valve 51 to start closed, but almost immediately tank pressure reaches about 1 /2 p.s.i. because almost all the volume of chamber 20 is occupied by water. At this pressure, water will flow through the line 27 into bowl 15. Because inlet pressure is normally in the order of 20 p.s.i. valve 51 must begin to relieve the excess pressure almost immediately to limit pressure in chamber 20 to only that required to force water into the bowl, and does so by discharging a substantial amount of the air flow through valve 51.

As pressure begins to build up in chamber 62, the load applied to the diaphragm 57 assists in opening valve 51 resulting in a gradual transfer of load from diaphragm 82 to diaphragm 57 until flushing is complete, at which point all of the load is carried by diaphragm 57. The pressure in chamber 62 continues to rise causing the valve 51 to continue to open until the fully open position is reached at which time sufiicient air will flow through the venturi to create a vacuum in lines 47 and 48. When vacuum is applied through line 75 to diaphragm 82, it is free to move to the right and will separate from the diaphragm 82 at 87 so that the force on diaphragm 82 no longer eifects the position of valve 51.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention.

What is claimed is:

1. In a self-contained sewage system having a main holding tank, a liquid reservoir to receive filtered liquid from said holding tank, a flush bowl including a flushing manifold connected to direct a flow of flushing liquid from said reservoir through said bowl, and an outlet connected from said bowl into said tank; an improved pneumatic system for applying pressure to the reservoir to empty the liquid contained therein into said flushing manifold and thereafter to refill said reservoir with filtered liquid from said main holding tank, said system comprising a venturi connected to a source of air and having a vacuum line connected to said reservoir;

a normally closed valve located downstream of said venturi to restrict air flow through said venturi thus causing a positive pressure to be applied to said reservoir through said vacuum line;

pneumatic time delay means for opening said normally closed valve after a predetermined time period to permit air to flow freely through said venturi and therefore to cause a subatmospheric pressure to be applied through said vacuum line to said reservoir;

inlet valve means between the source of air and said venturi; and

means connected to said inlet valve means and responsive to the liquid level in said reservoir for closing said inlet valve means after said reservoir is filled with liquid to a predetermined level thereby terminating the flow of air to and through said venturi and said pneumatic time delay means.

2. A pneumatic system for applying pressure to a liquid containing reservoir for a predetermined time period to empty the reservoir of liquid, and thereafter for applying a subatmospheric pressure to said reservoir to cause it to refill with liquid to a predetermined level, said system comprising a venturi connected to a source of air and having a vacuum line connected to said reservoir;

a normally closed valve located downstream of said venturi to restrict air flow through said venturi thus causing a positive pressure to be applied to said reservoir through said vacuum line;

pneumatic time delay means for opening said normally closed valve after a predetermined time period to permit air to flow freely through said venturi and therefore to cause a subatmospheric pressure to be applied through said vacuum line to said reservoir;

inlet valve means between the source of air and said venturi; and

means connected to said inlet valve means and responsive to the liquid level in said reservoir for closing said inlet valve means after said reservoir is filled with liquid to a predetermined level thereby terminating the flow of air to and through said venturi and said pneumatic time delay means.

3. A pneumatic system of claim 2 further including means for partially opening said normally closed valve when the pressure in said reservoir reaches a predetermined level below said inlet pressure and automatically maintaining such pressure until overridden by said pneumatic time delay means.

4. The pneumatic system of claim 2 wherein said pneumatic time delay means is connected to said vacuum line from said venturi and operates to open said normally closed valve fully a predetermined time period after a positive pressure is applied to said vacuum line.

5. The pneumatic system of claim 2 wherein said inlet valve means comprises a body having formed therein a cavity and having an inlet connected to the source of air and having an outlet connected to said venturi;

a valve within said cavity to control the flow of air from said inlet to said outlet;

a diaphragm on the inlet side of said cavity connected to said valve said diaphragm forming first and second chambers wherein said first chamber is in constant communication with the source of air;

an opening through said diaphragm to equalize the pressure in said first and second chamber;

said diaphragm having an area in said second chamber larger than the area in said first chamber when said valve is closed causing said diaphragm to be urged toward said first chamber keeping said valve in the closed position; and

means in said second chamber operable to relieve the pressure in said second chamber thereby causing said diaphragm to move toward said second chamber and open said valve;

and wherein said means for closing said inlet valve means includes means responsive to subatmospheric pressure in said vacuum line of said venturi to reseal said second chamber thereby allowing the pressure therein to increase, move said diaphragm toward said first chamber, and close said valve between said inlet and said outlet.

References Cited UNITED STATES PATENTS 2,417,994 3/1947 Sheets 251-24 2,999,797 9/1961 Campbell 210-62 XR 3,067,433 12/1962 Dietz et al. 4-90 XR 3,380,348 4/1968 Krofike 137624.18 XR 3,418,664 12/1968 Carmichael et a1. 4-115 3,487,475 1/1970 Minnear 4 10 LAVERNE D. GEIGER, Primary Examiner R. I. SMITH, Assistant Examiner 

